With the provision that the idea of "polishing" feed ramps is NOT "like a mirror", it's to get a smooth surface that bullets won't catch on.
Too many people hear "polish" and think "like a mirror" and in trying for that mirror shine, they remove metal and alter the ramps, often ruining guns.
What we actually mean by "polish" is really de-burr or smooth any machine marks, and even then they don't have to be perfectly removed.
So why do custom guns have a mirror bright ramp?
Simple.
The customer pays for a polished ramp and seeing just a smooth ramp decides the gunsmith either forgot to do it, or he ripped the customer off by charging for something not done.
So, the gunsmith polishes to a mirror polish so the customer knows he got what he paid for.
The difference is, the custom 'smith knows how to give a mirror shine without over doing it and damaging the gun.